Requirement Decomposition Guidance
How to write lower-level requirements that add value beyond the parent.
What a good decomposed requirement should do
- Clearly describe what the Ground Systems element provides, enables, or supports.
- Add meaningful value beyond restating the parent requirement.
- Stay within Ground Systems scope.
- Use precise, technically scoped language.
- Trace cleanly to the correct parent requirement.
What to avoid
- Repeating the parent requirement with no added specificity.
- Vague phrases such as "essential components" unless clearly defined.
- Claiming Ground Systems performs analytics or maintenance decisions if it only provides data access.
- Implying ownership of Air Vehicle systems.
How to write requirement text
Identify the major nouns. Confirm their definitions. State the Ground Systems function clearly. Keep the sentence single-purpose and testable.
How to write rationale
Explain why the requirement exists, how it supports the parent, applicable standards or AFIs, definitions, and interface context. Include SME-confirmed assumptions.
How to check parent-child relationships
Review the RV package. Confirm each child traces to the correct parent. Break and reconnect any incorrect or outdated links.
Bad practice vs. better approach
| Bad Practice | Why It Is a Problem | Better Approach |
|---|---|---|
| Air Vehicle Instrumentation shall support CBM+. | Restates the parent. Does not say what Ground Systems provides. Implies Ground Systems performs CBM+. | Air Vehicle Instrumentation shall provide the capability to access air vehicle data to support CBM+ and Program Health Monitoring activities. |
| Ground Systems shall include essential components for sustainment. | "Essential components" is undefined. Not testable. No scope boundary. | Air Vehicle PSE shall provide the equipment required for O-Level fault isolation and maintenance of the mission system power pack. |
| Ground Systems shall own the flight data recorder. | Overstates ownership. FDR is an Air Vehicle item. | Air Vehicle Instrumentation shall interface with the common junction panel to access aircraft data for sustainment and health monitoring. |
| The cradle shall be sustainable. | Vague. Does not specify level of maintenance. | Mission System Power Pack Cradle shall support O-Level maintenance and troubleshooting of the mission system power pack. |
Pre-submit checklist
- Does this requirement add value beyond the parent?
- Does it stay within Ground Systems scope?
- Does it avoid claiming analytics or maintenance decision ownership?
- Are all major nouns clearly understood?
- Are spelling and terminology correct?
- Is the rationale clear?
- Does the requirement trace to the correct parent?